1. Field of the Invention
The present invention relates generally to tamper-indicating closures for containers, and more particularly to a tamper-evident plastic closure including a pilfer band having container-engaging projections or tabs to facilitate application of closure to a container with high-speed application equipment.
2. Description of the Related Art
Tamper-indicating or tamper-evident container closures are well-known. For example U.S. Pat. No. 4,938,370 to McBride, which is hereby incorporated by reference in its entirety, discloses tamper evident plastic closures for use in connection with bottles or like containers having a threaded neck and a locking ring. The tamper evident function is there provided by a pilfer band which is initially attached to the closure cap via a score line, but which breaks or separates from the closure cap and remains on the bottle when the closure cap is unscrewed or otherwise removed from the bottle for the first time. The pilfer band includes tabs or projections which engage the threads or locking ring of the bottle so as to resist the removal of the pilfer band. The tabs must be capable of permitting passage of the threads and locking ring as the closure is applied to the bottle in conventional high speed application equipment, but must nonetheless reliably retain the pilfer band on the bottle when the cap is removed for the first time by the consumer. For this purpose, the tabs of McBride are flexible tabs which are capable of pivoting into either of two modes of tamper indication.
It is also known to provide the pilfer band with a weakened region in the form of a vertical line of reduced thickness which may be molded into the plastic closure. The presence of the weakened region results in a preferential failure of the pilfer band at the weakened region due to hoop stresses so that the pilfer band breaks and does not fully separate from the closure cap when the closure cap is first removed from the bottle. The pilfer band therefore remains with the closure cap, which is desirable for use with returnable bottles. Although not shown in McBride, such a weakened region can also be incorporated into the pilfer bands of closures based upon this patent.
More recently, there has been developed a tamper indicating plastic closure whose pilfer band has rigid tabs which do not pivot into the two different modes of tamper indication. However it has been found that the tabs adjacent the weakened region may break or permanently deform upwardly against the interior wall of the pilfer band during the application of the closure to a container or bottle using high speed application equipment. Those tabs which are so bent may be unable to participate in the subsequent retention of the pilfer band on the bottle during the removal of the closure cap. Reliable tamper indication might therefore be impaired.